Axial fluctuation in movement of a rotating recording disc during recording or playback, particularly the thin flexible sheet or foil type discs, presents a problem with the optical playback kind of machines. Electro-mechanical approaches to solving this problem are shown in U.S. Pat. Nos. 4,051,529 and 4,058,834, for example.
Apparatus for playing thin flexible foil recordings is shown in U.S. Pat. No. 4,060,248 as including a transparent adapter support disc which supports and rotates with the foil recording. Air admission apertures are shown near the hub of this support disc to admit air in between the rotating foil recording and the rotating planar face of the support disc. The air is disclosed to pass between the rotating adapter disc and the rotating recording, due to centrifugal force, to produce an air gap or spacer, of thickness of approximately 0.5 millimeter, so that dust particles cannot become trapped between the two discs.
U.S. Pat. No. 4,068,851 dicloses playback apparatus including a disc housing and positioning feature.
U.S. Pat. No. 3,927,252 shows a disc stabilizer system including two stabilizer blocks spacially related on either side of a video disc which create aerodynamic air forces between the disc and the blocks to balance the blocks between the disc and resilient biasing elements.
Air bearings, i.e., air utilized as the lubricant between relatively moving surfaces, are rather commonly known and utilized.